1. Field of the Invention
This invention concerns novel derivatives of certain 8-(lower alkyl)bicyclo[4.2.0]octanes and pharmaceutically acceptable salts and esters thereof, their use in treating cardiovascular disorders, pharmaceutical compositions containing these compounds, and methods of preparing such compounds.
2. Related Disclosures
Bicyclo[4.2.0]oct-2-en-7-one is readily prepared from 1,3-cyclohexadiene (Tetrahedron, 27:615, 1971). This has been used as an intermediate in a prostaglandin synthesis (Tetrahedron Lett., 3091, 1973).
Several prostaglandin analogues are known which contain bicyclic all-carbon skeletons. Carbacyclin contains a bicyclo[3.3.0]octane skeleton, and is described in several publications (J. Chem. Soc., Chem. Commun., 1067, 1978, Tetrahedron Lett., 3743, 1978; Tetrahedron Lett., 433, 1979; Tetrahedron Lett., 2807, 1979; J. Org. Chem. 44:2880, 1979) and patents (Belgium Patent No. 874, 135; British Patent No. 2,014,143; French Patent 2,424,908; Ger. Offen. 2,904,655; Japanese Patent K 79,117,450; Netherthland Patent Application Nos. 7,901,076 and 8,003,579; S. African Patent No. 79 00 176). Numerous analogues of carbaprostacyclin are described (U.S. Pat. No. 4,306,076; Ger. Offen. 3,146,278; Ger. Offen. 3,204,443; Prostaglandins, Leukotrienes, Med., 9:307, 1982; J. Org. Chem. 48, 5341, 1983; Tetrahedron Lett., 3493, 1983; Biochem. Pharmacol. 32:2405, 1983; Prostaglandins, Leukotrienes, Med. 11:391, 1983).
Synthetic prostaglandins (homo PGE.sub.2 and homo PGF.sub.2.alpha.) have been prepared with the hydroxyl function and lower side chain trans-opposed in a 6-membered ring (Tetrahedron Lett., 3327, 1971).